Damage to knee ligaments and menisci

Knee trauma often results in damage to the outer (medial and lateral collateral) or inner (anterior and posterior cruciate) ligaments or a tear of the meniscus. Symptoms of knee ligament and meniscus injury include pain, hemarthrosis, instability (in severe injuries), and joint block (in some meniscus injuries). Diagnosis is by examination, MRI, or arthroscopy. Treatment includes rest, ice, compression, elevation, and, for severe tears, casting or surgery.

The structures located mainly outside the joint and helping to stabilize it include muscles (e.g., the quadriceps, semimembranosus muscles), their attachment sites (e.g., the pes anserinus), and extra-articular ligaments. The lateral collateral ligament is an extra-articular structure, the median (tibial) ligament has a superficial extra-articular part and a deep part, the latter being part of the joint capsule.

The knee joint structures that provide stabilization include the joint capsule, the posterior cruciate ligament, and the well-vascularized anterior cruciate ligament. The medial and lateral menisci are intra-articular cartilaginous structures that provide shock absorption of the articular cartilage and also participate to a limited extent in joint stabilization.

The most commonly injured ligaments are the medial collateral ligament and the anterior cruciate ligament. The typical mechanism of injury to the knee ligaments is an inward and medial force, usually combined with moderate external rotation and flexion (as occurs in a football trip). In such cases, the medial collateral ligament is usually injured first, followed by the anterior cruciate ligament, and finally the medial meniscus. The next most common mechanism is an outward force, often injuring the lateral collateral ligament, the anterior cruciate ligament, or both. Anterior or posterior force and hyperextension of the knee often result in cruciate ligament injury. Simultaneous weight bearing and rotation predispose to meniscal injury.

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Symptoms of knee ligament and meniscus damage

Swelling and muscle spasm progress over the first few hours. With grade II injuries, pain is usually moderate to severe. With grade III, pain is minor and, surprisingly, some patients can walk without support. An audible click is unusual; its presence suggests a tear of the anterior cruciate ligament. The presence of hemarthrosis also indicates injury to the anterior cruciate ligament and probably other intra-articular structures. However, with severe grade III tears of the medial collateral ligament and anterior cruciate ligament, hemarthrosis may not be present because the joint capsule is damaged and blood may simply leak out. The area of greatest tenderness often corresponds to the damaged structure; with a medial meniscus tear, tenderness on palpation of the inner surface of the joint, with a lateral meniscus injury, tenderness on palpation of the outer surface of the joint. These injuries can also cause swelling and, occasionally, limitation of passive motion (so-called jamming).

Diagnosis of knee ligament and meniscus damage

In a patient with severe instability, spontaneous reduction of the knee dislocation should be suspected, in which case emergency angiography is indicated. In other cases, the knee joint should be fully examined, primarily by assessing its extension.

There are various methods for detecting other injuries. In the Epley test, the doctor flexes the knee joint of the patient lying face down to 90'. Pain during compression and rotation of the knee joint gives reason to think about a meniscus tear. Pain during distraction and rotation of the knee joint gives reason to think about damage to the ligaments or joint capsule. To assess the condition of the collateral ligaments, the patient is laid on his back, bending the knees to approximately 20 °, achieving complete muscle relaxation. The doctor places one hand on the joint on the side opposite the ligament being examined. With the other hand, he clasps the heel, turns the shin outward to assess the internal collateral ligament, inward - the external. Moderate instability after an acute injury gives reason to think about a meniscus or cruciate ligament tear. The Lachman test is most sensitive for acute ruptures of the anterior cruciate ligament. The doctor supports the thigh and shin of the lying patient with knee flexion to 20 °. Excessive passive movements of the tibia anterior to the femur suggest a significant rupture.

If stress testing is difficult (e.g., due to pain or muscle spasm), the examination should be repeated after local anesthetic injection or under systemic analgesia and sedation, with a follow-up examination in 2-3 days (when swelling and muscle spasm have subsided), or MRI or arthroscopy should be performed. If serious injury cannot be ruled out, MRI or arthroscopy is clinically indicated.

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Treatment of knee ligament and meniscus damage

Evacuation of a large amount of fluid from the joint may reduce pain and spasm. Most grade I and mild/moderate grade II injuries can be treated initially with rest, ice, compression, elevation, and immobilization of the knee at 20° flexion with commercially available devices. Most grade III, severe grade II, and most meniscal injuries require casting for 6 weeks or more. However, some grade III knee ligament and meniscal injuries of the medial collateral ligament, anterior cruciate ligament, and meniscus may require arthroscopic reconstruction.